Vital Capacity Calculator

% Predicted	Severity
≥ 80%	Within normal limits
65-79%	Mildly reduced
50-64%	Moderately reduced
< 50%	Severely reduced

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Walk-through

How to Use This Calculator

3 steps

1

Enter your age, height, and sex

Choose your height units (imperial inches or metric centimeters), then enter your sex, age in years, and standing height. The calculator uses sex-specific coefficients, so results differ between the male and female equations even at the same age and height.

2

Read your predicted VC

The Predicted VC tab updates instantly and shows the vital capacity expected for someone of your age, height, and sex, in liters. This is a population-average reference point, not a measurement of your actual lungs.

3

Compare a measured value (optional)

If you have a spirometry report, enter the measured VC in liters. The % Predicted tab then shows your result as a percentage of the prediction, with a plain-language severity read based on standard percent-predicted bands.

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Reference

Formula & Methodology

3 formulas

Predicted VC (male)

VC (L) = 0.052 x height_cm - 0.022 x age_yr - 3.60

The Baldwin, Cournand & Richards (1948) predicted-vital-capacity regression for males, using standing height in centimeters and age in years.

Predicted VC (female)

VC (L) = 0.041 x height_cm - 0.018 x age_yr - 2.69

The Baldwin, Cournand & Richards (1948) predicted-vital-capacity regression for females. The smaller height coefficient and different intercept reflect average differences in thoracic dimensions between the sexes.

Percent predicted

% predicted = (measured VC / predicted VC) x 100

Once you enter a measured VC (in liters, from a spirometry report), this compares it against your predicted value. Values at or above 80% of predicted are generally considered within normal limits.

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High YMYL

Trust, Methodology & Sources

Reviewed by Calculover Editorial Team · Updated 2026-07-22 · 2 sources

Editorial accountability

Author: Calculover Clinical Content Team - Health calculator content author

Owner: Calculover Editorial Team - Health & Fitness category owner

Reviewer: Calculover Editorial Team - Clinical content reviewer

Last reviewed: 2026-07-22

Last verified: 2026-07-22

Data effective: 2026-07-22

Methodology

Predicted vital capacity uses the Baldwin, Cournand & Richards (1948) linear regression against standing height (cm) and age (years), with separate coefficients for males and females. Percent predicted divides a user-entered measured VC by this predicted value; severity bands (normal >= 80%, mild 65-79%, moderate 50-64%, severe < 50%) follow a simplified scale broadly consistent with ATS/ERS interpretive guidance for restrictive spirometry patterns.

Assumption: Height is standing height without shoes; age is in whole years.

Assumption: The Baldwin (1948) reference population may not reflect the range of body types and ethnic backgrounds seen in modern multi-ethnic reference equations, so predicted values are an approximation.

Assumption: A measured VC entered by the user is assumed to come from a properly performed spirometry maneuver — the calculator cannot verify test quality.

Limitations & guidance

This tool does not diagnose any respiratory condition. A low percent-predicted VC alone does not confirm a restrictive pattern — that requires the FEV1/FVC ratio and often additional testing (e.g., total lung capacity).

Different predicted-VC reference equations (populations, eras, ethnic-specific standards) can yield noticeably different predicted values for the same person; a clinical pulmonary function report may use a different reference than the one used here.

This calculator is intended for adults; predicted-lung-function equations for children and adolescents require pediatric-specific reference equations, not the adult regression used here.

Professional guidance: This calculator is for educational purposes only and does not provide medical advice, diagnosis, or treatment. Discuss any spirometry results, respiratory symptoms, or lung-function concerns with a qualified healthcare provider.

Primary sources

Baldwin ED, Cournand A, Richards DW Jr. "Pulmonary insufficiency." Medicine. 1948;27(3):243-278.

American Thoracic Society / European Respiratory Society — Standardisation of Spirometry and Interpretive Strategies

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Glossary

Key Terms Explained

6 terms

Vital capacity (VC) The maximum volume of air a person can exhale after inhaling as deeply as possible, measured without regard to how fast the breath is exhaled. Reported in liters.

Forced vital capacity (FVC) The same maximal exhalation as VC, but performed as fast and forcefully as possible. In healthy lungs FVC and VC are close; in obstructive disease (like COPD), FVC can be noticeably lower than a slower VC maneuver because rapid exhalation traps extra air.

Percent predicted A measured value expressed as a percentage of the value predicted for someone of the same age, height, and sex. It normalizes results so people of different body sizes can be compared on the same scale.

Spirometry A breathing test that measures how much air a person can move in and out of the lungs and how quickly, used to screen for and monitor lung conditions.

Restrictive pattern A spirometry pattern where lung volumes (VC, FVC, and total lung capacity) are reduced relative to predicted, typically with a normal or increased FEV1/FVC ratio — seen in conditions that limit how much the lungs or chest wall can expand.

Reference (predicted) equation A regression equation, derived from measurements in a healthy reference population, that estimates the expected lung-function value for a person's age, height, and sex. Different reference equations (and populations) can produce somewhat different predicted values.

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Scenarios

Real-World Examples

3 worked examples

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Healthy adult male

Predicted-only

Sex Male Age 40 years Height 70 in (178 cm)

Predicted VC = 0.052 x 178 - 0.022 x 40 - 3.60 = 4.79 L. With no measured value entered, this is simply the reference point for someone of this age, height, and sex — there's nothing to interpret as normal or abnormal yet.

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Normal spirometry result

Measured value within normal limits

Sex Female Age 30 years Height 65 in (165 cm) Measured VC 3.6 L

Predicted VC = 0.041 x 165 - 0.018 x 30 - 2.69 = 3.535 L. A measured 3.6 L is about 102% of predicted — comfortably within normal limits, with no restrictive pattern suggested.

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Reduced measured VC

Possible restrictive pattern

Sex Female Age 30 years Height 65 in (165 cm) Measured VC 1.5 L

Against the same 3.535 L prediction, a measured 1.5 L is about 42% of predicted — in the severely-reduced range. This pattern (low VC, normal or high FEV1/FVC ratio) is consistent with a restrictive process and warrants a clinician's review alongside the full spirometry report.

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Deep Dive

Understanding the Vital Capacity Calculator

3 chapters · 4 min read

This calculator estimates the vital capacity (VC) expected for someone of a given age, height, and sex, using a classic predicted-VC regression from pulmonary physiology. If you have a measured VC from a spirometry test, it also shows that result as a percentage of the prediction, which is how clinicians typically frame lung-function results.

How the Vital Capacity Calculator works

Predicted VC is computed with the Baldwin, Cournand & Richards (1948) regression equations, which relate vital capacity to standing height and age using separate coefficients for males and females. These are among the earliest and most widely reproduced predicted-VC equations in pulmonary physiology textbooks. Like all predicted-lung-function equations, the coefficients were derived from measurements in a specific reference population, so any single equation is an approximation rather than a universal constant — modern clinical spirometers may use a different, more contemporary reference set.

When you enter a measured VC (from a spirometry test), the calculator divides it by your predicted value to get a percent-predicted figure, then bands that percentage using a simplified normal / mild / moderate / severe scale broadly consistent with ATS/ERS interpretive guidance for restrictive patterns.

Inputs and what they mean

Sex and age (in years) are used directly in the regression. Height should be standing height without shoes — a few centimeters of error shifts the predicted value only slightly, since the height coefficient is small. Measured VC is optional and should come from an actual spirometry report, in liters; without it, the calculator only shows the population-predicted reference value, with nothing to compare it against.

Limits and edge cases

This calculator is for education, not diagnosis. Predicted-VC equations vary by reference population, and the Baldwin equation used here predates more recent multi-ethnic reference standards, so results may differ from a clinical pulmonary function report using a newer or population-specific equation. VC alone also cannot distinguish a restrictive from an obstructive pattern — that requires the FEV1/FVC ratio and, often, additional tests like total lung capacity (via body plethysmography or gas dilution). Anyone with an unexpectedly low measured VC, or any respiratory symptoms, should discuss the full spirometry report with a clinician rather than relying on this calculator alone.

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Questions

Frequently Asked Questions

6 questions

What does the Vital Capacity Calculator actually compute?+

It estimates the predicted vital capacity (in liters) for someone of a given age, height, and sex, using the Baldwin, Cournand & Richards (1948) regression equations. If you also enter a measured VC from a spirometry report, it shows that value as a percentage of the prediction with a plain-language severity read.

How accurate is this calculator?+

The Baldwin equations are a long-standing, widely-cited predicted-VC reference, but like any regression they were derived from a specific study population, so predicted values from different reference equations can differ by several percent for the same person. Treat the predicted value as a reasonable population-average estimate, not an exact figure for your individual lungs — a clinical pulmonary function report may use a different, more current reference standard.

What units does the Vital Capacity Calculator expect?+

Age is in years, height can be entered in either inches (imperial) or centimeters (metric) using the toggle, and both predicted and measured vital capacity are in liters. The calculator converts imperial height to centimeters internally before applying the regression.

Can I share my results?+

Yes — the calculator encodes your inputs into the page's URL, so copying the URL (or using the Share button) is enough to send the same scenario to someone else.

Where does the predicted-VC formula come from?+

It's from Baldwin ED, Cournand A, and Richards DW Jr., "Pulmonary insufficiency," published in Medicine in 1948 — one of the earliest and most frequently reproduced predicted vital-capacity regressions in pulmonary physiology references.

What's the difference between vital capacity and FEV1 or FVC?+

Vital capacity (VC) is the total air moved in a slow, unhurried maximal breath. Forced vital capacity (FVC) is the same maneuver done as fast as possible, and FEV1 is the air exhaled in the first second of that forced breath. FEV1/FVC ratio distinguishes obstructive patterns (low ratio) from restrictive ones (low VC/FVC with a normal or high ratio) — this calculator only addresses the VC side of that picture.

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